Lacerations and puncture wounds are common presentations to the emergency department (ED). Most of these wounds are minor, but a significant number can be complicated with foreign bodies. It is important to have a high index of suspicion and thoroughly evaluate all wounds for foreign bodies. A wound that does not heal appropriately or develops an abscess should be evaluated for a retained foreign body (1,2,3,4,5,6,7).

Retained foreign bodies place children at a higher risk for infection and scarring. Foreign bodies can migrate, thereby causing neurological problems or other injuries.

Retained foreign bodies account for a significant number of malpractice claims. The management of foreign bodies is both high risk and very common, highlighting the importance of proper management of these patients.

The types and locations of foreign bodies change with age. Infants crawl on all fours, so their hands and knees are at risk for foreign bodies. As children begin to walk, they are at risk for puncture wounds to their feet. These injuries occur during adolescence, but teenagers may also be involved in violence and thus are at risk for foreign bodies from trauma, including bullets, knives, and other sharp objects.

As with all wound management, a thorough history and physical examination is necessary to determine the risk of foreign bodies as well as what type of foreign bodies might be encountered. The history and physical will be dependent on the patient’s age and ability to cooperate.

Once the presence of a foreign body has been confirmed, a determination must be made as to the most appropriate procedure, optimal setting, and best clinician to perform the foreign body removal. There are a number of factors involved in making such decisions. The patient’s ability to cooperate with the procedure is paramount. An attempt to remove a foreign body from an uncooperative patient is likely to fail and can be dangerous. to The location of the foreign body will also dictate where the removal should be accomplished as well as by whom. If there is a superficial foreign body that is visualized and in a safe anatomical location, it can be removed by the physician in the ED. If the foreign body is located next to vital or easily injured structures, it should be removed by the appropriate surgical subspecialist under controlled conditions with the use of procedural sedation and analgesia or in the operating room. If the emergency physician decides to proceed with the removal of the foreign body, a time limit should be set, usually 30 minutes, and strictly followed. The entire plan should be discussed with the parents, as well as the alternative course if the initial procedure is unsuccessful.

Foreign bodies vary in their ability to cause inflammation in the body. The majority of the subcutaneous foreign bodies are glass, wood, or metal. Glass and metal are usually benign and do not cause significant acute inflammation. They can cause injury due to migration as well as lacerate tendons, nerves, or muscles as they enter the body. They may cause chronic inflammatory changes over time, which may appear as osteolytic lesions or pseudotumors on x-rays (8,9). Even benign foreign bodies can cause infection if they are contaminated with bacteria or bring bacteria from the skin as they enter the body.

The body’s reaction to a subcutaneous foreign substance depends on the degree of inflammatory response that is stimulated. Polymorphonuclear neutrophils represent the body’s initial reaction. These cells release hydrolytic enzymes that cause destruction of the foreign body and pustule formation. This reaction can result in the extrusion of the foreign body or lead to infection and abscess formation. Less
inflammatory foreign bodies will cause granuloma formation as macrophages wall off the foreign body with fibrin and collagen. Granulomas may still become infected due to chronic inflammation.

Wooden foreign bodies cause inflammatory reactions in most patients (9,10). If not immediate, there will eventually be inflammatory changes. Other plant material, including thorns and spines from cacti, is also likely to trigger significant inflammation (10). These foreign bodies are at high risk for infection and may also carry fungi, leading to phycomycoses.

Graphite foreign bodies, usually from a pencil, can lead to tattooing of the tissue. Embedded silica can cause granulomas months and even years after implantation (11). A commonly encountered foreign body is rubber from the sole of a shoe, usually a sneaker. Rubber is an excellent growth medium for bacteria, especially Pseudomonas organisms (12). Puncture wounds through a sneaker are at high risk for infection, including cellulitis, perichondritis, and ultimately osteomyelitis.

The location of the foreign body affects the difficulty of finding and removing it as well as influences potential complications. The hand is one of the most common areas where foreign bodies are found. There are multiple structures and tissue planes in the hand. This makes locating foreign bodies by exam or imaging difficult. The mobility of the hand can cause a foreign body to enter in one location but quickly relocate a distance away from the entrance wound. The number of relatively superficial tendons, ligaments, nerves, and vessel also make attempts at foreign body removal more difficult and potentially more dangerous. The foot, especially the sole, is also a common location for foreign bodies. Often the foreign body will be contaminated with additional material. A puncture wound from a nail can leave a foreign body in the soft tissue, such as the nail, a portion of the shoe, sock material, or dirt. These wounds are at high risk for infection. Most skin infections are due to Staphylococcus aureus or group A streptococci. Puncture wounds of the feet, especially through sneakers, are also at risk for infections with Pseudomonas aeruginosa. Other organisms that cause foreign body–associated infections include non–group A streptococci, clostridia, and various fungal species. The thickness of the sole of the foot makes the examination harder and the removal of any foreign bodies difficult.

Locating a foreign body is often a difficult process. It begins with entertaining the suspicion of a foreign body. The first step is to obtain an adequate history. A physical examination will identify some foreign bodies and give clues to the possible presence of others. A foreign body is often not obvious on the first inspection of the wound. For example, glass is very difficult to visualize in a wound. Still, wounds less than 5 mm in depth are unlikely to retain a glass foreign body (13). Physical examination findings suspicious for a foreign body include pain out of proportion to the wound, pain on deep palpation over the wound, pain with passive movement of the area, pain over a palpable mass, and skin discoloration. Wounds most likely to have a glass foreign body include puncture wounds, wounds to the head or feet, and wounds from a motor vehicle collision (14).

An important adjunct in determining the presence of or helping to localize a foreign body is imaging. The best modality depends on the type of foreign body suspected as well as its location. The most commonly utilized modality is plain radiography.

Plain radiographs are able to identify most glass or metallic foreign bodies. Aluminum is difficult to detect on radiographs when ingested, but aluminum subcutaneous foreign bodies are usually visible. Glass is usually visible down to 1 to 2 mm in size. Overlying bone reduces the ability to visualize glass foreign bodies (15,16,17,18,19). Gravel 1 to 2 mm in diameter can be visualized in 97% of cases, but gravel less than 0.5 mm in diameter can seen in fewer than 75% of cases (20). Wood, vegetable material, and plastic are only rarely visible on plain radiographs (15%). Wood is virtually impossible to visualize after 48 hours because the air trapped in the wound is absorbed and the density of the wood then matches the surrounding tissue. Subcutaneous air on a radiograph may be indicative of the location of a foreign body that is itself not visible (21). It is important to obtain multiple views at opposite angles to allow localization in multiple planes. Underpenetrated images are often helpful in visualizing foreign bodies. Digital radiography systems can adjust the brightness and contrast to improve visualization. Radiopaque surface markers at the entrance site can also be helpful in localizing the foreign body. Useful markers include ECG electrodes, paper clips, and needles.

Fluoroscopy is a less frequently used form of plain radiography. Because fluoroscopy provides continuous images, localizer needles can be placed and moved to the foreign body under direct imaging. Once the foreign body is localized, it can be removed by following the localizing needles down to where it is. The disadvantages of fluoroscopy include the lack of availability, the high radiation dose, and the prolonged time required for the procedure.

Computed tomography (CT) also uses x-rays, but it is better able to detect small differences in density. Foreign bodies that are not visible in plain radiographs may be visible on a CT scan. Because of the three-dimensional ability of CT, it is able to visualize foreign bodies behind bone and more accurately locate foreign bodies near vital structures. CT is the modality of choice for foreign bodies of the head (22).

Magnetic resonance imaging (MRI) also allows three-dimensional imaging. Since it does not use x-rays, it is useful for locating foreign bodies that have a density similar to that of the surrounding tissue. Wood, vegetable matter, and plastic are much better visualized on an MRI scan. Surrounding inflammation or edema are also better visualized. MRI is a poor choice for metallic foreign bodies, since they may cause
significant artifact. Of more concern is the potential of MRI scanning to cause the migration of metallic foreign bodies. MRI should be used with caution in locating foreign bodies in the head, eye, or neck (22,23).

A disadvantage of both CT and MRI is that they require a still and cooperative patient. In some cases, the patient may require sedation, which can make these imaging techniques complicated and prolonged. CT scanning and sometimes MRI scanning require separation of the child from the parents as well, which can make a cooperative child uncooperative. CT and MRI should be reserved for high-risk patients or in cases where plain radiography is inconclusive.

Ultrasound is emerging as one of the most important techniques for locating foreign bodies. It is excellent at visualizing radiolucent subcutaneous foreign bodies. The sensitivity and specificity of ultrasound in locating foreign bodies exceed 90% in many studies. Because ultrasound can be performed in real time, it allows direct visualization of instruments moving toward the foreign body. Another advantage is that neither the patient nor the operator are exposed to radiation. The disadvantages include a high degree of operator dependence and difficulty visualizing objects close to bone or in wounds that contain gas in the tissue (Chapter 135) (24,25,26,27,28).

Once a foreign body has been located by exam and imaging, the next step is to determine the risks and benefits of removal. This is a multifactorial process. Not all foreign bodies require removal. The benefits of removal include reduced risk of infection, often decreased pain, and decreased risk of late sequelae. These benefits are fairly consistent, so the primary question is, What is the risk of this specific foreign body to the patient?